1. Field of the Invention
The present invention relates to a substrate processing apparatus for cleaning a substrate with a brush. Examples of the substrate to be processed include a semiconductor wafer, a liquid-crystal-display-device substrate, a plasma-display substrate, an FED (Field Emission Display) substrate, an optical-disk substrate, a magnetic-disk substrate, a photomagnetic-disk substrate, a photomask substrate and the like.
2. Description of Related Art
A sheet-feed type processing unit used in a substrate processing apparatus for producing semiconductor devices or liquid crystal display devices, has, for example, a spin chuck for substantially horizontally holding and rotating a substrate and a nozzle for supplying a treating liquid to the substrate thus held by the spin chuck. The processing unit for scrubbing-cleaning a substrate further has a brush for scrubbing-cleaning the substrate held by the spin chuck (See for example Japanese Unexamined Patent Publication No. 2001-9388).
The brush is held by a holding arm capable of pushing the brush to a substrate. The holding arm is connected to a brush moving mechanism arranged to move the holding arm such that the brush is moved toward or away from the substrate and that the brush, as being in contact with the substrate, is moved along the substrate.
At the time of scrubbing-cleaning the top face of the substrate, for example, a treating liquid is supplied to the substrate top face from a nozzle while the substrate is being rotated in a horizontal plane by the spin chuck. Further, with the brush pushed to the top face of the substrate by the holding arm, the brush moving mechanism moves the brush along the top face of the substrate.
The holding arm has, for example, a housing, a shaft of which lower end projects from the bottom of the housing, and a brush pushing actuator disposed above the shaft in the housing.
With the brush being in contact with or in the vicinity of the substrate held by the spin chuck, the actuator applies a load to the shaft. This causes the brush attached to the lower end of the shaft to be pushed to the surface of the substrate.
In apparatus of prior art, since the brush pushing actuator is disposed above the shaft, the holding arm is increased in vertical height. Accordingly, the processing unit having the holding arm mounted, is disadvantageously increased in vertical height.
On the other hand, when a substrate processing apparatus has a plurality of processing units, there are instances where the processing units are vertically stacked in order to restrain their footprint from being increased. When a substrate processing apparatus having such an arrangement uses processing units each having a holding arm having the arrangement above-mentioned, the substrate processing apparatus in its entirety is disadvantageously increased in vertical height. This makes it difficult to design the substrate processing apparatus within the height of the ceiling of a clean room. Alternatively, it will be difficult to do maintenances even though the designing in such a spatial limit is possible.